Corrosion inhibitor compositions comprising tetrahydrobenzotriazoles and other triazoles and methods for using same

ABSTRACT

A composition with a corrosion inhibitor component having one or more tetrahydrobenzotriazoles and one or more other triazoles; wherein the tetrahydrobenzotriazoles are in a weight ratio to the other triazoles such that the composition decreases the General Corrosion rate, as measured by copper electrodes in the presence of 10 ppm sodium hypochlorite, by at least about 0.05 mpy relative to a corrosion inhibitor component which is 100% of the other triazoles. Also, a method of using this composition to inhibit corrosion of a metal component which has a metal or metal alloy which is corrodible in the presence of copper or copper corroding agents.

FIELD OF THE INVENTION

The present invention generally relates to a corrosion inhibitingcomposition comprising one or more tetrahydrobenzotriazoles and one ormore other triazoles. The present invention also generally relates to amethod for inhibiting corrosion of a metal component which is corrodiblein the presence of copper or copper corroding agents by contacting thatmetal component with a corrosion inhibiting amount of this composition.

BACKGROUND

In many industrial processes, undesirable excess heat may be removed bythe use of heat exchangers in which aqueous systems may be used as theheat exchange fluid. Various metals and metal alloys, such as copper andcopper-bearing alloys (e.g., brass), may be used in the fabrication ofsuch heat exchangers, as well as in other parts in contact with thecooling water, such as pump impellers, stators, valve parts, etc.Aqueous systems such as those cooling fluids may be corrosive towardsthese copper-containing metal parts due to the presence of aggressiveions and by the intentional introduction of oxidizing substances forbiological control. The consequences of such corrosion are the loss ofmetal from the equipment, potentially leading to failure or requiringexpensive maintenance, creation of insoluble corrosion product films onthe heat exchange surfaces, potentially leading to decreased heattransfer and subsequent loss of productivity, and discharge of copperions which may then “plate out” on less noble metal surfaces and maycause severe galvanic corrosion, a particularly insidious form ofcorrosion. Also, copper is a potentially toxic substance, so itsdischarge to the environment is undesirable.

It is common practice to introduce corrosion inhibitors into suchcooling water systems, as well as other aqueous and nonaqueous systems.These corrosion inhibitors may interact with the metal/metal alloy todirectly produce a film which is resistant to corrosion, or mayindirectly promote formation of protective films by activating themetal/metal alloy surface so as to form stable oxides, other insolublesalts, etc. Such protective films may not be completely stable, but mayinstead degrade under the influence of the aggressive conditions in thecooling water. Because of this degradation, a constant supply ofcorrosion inhibiting substances in the cooling water may be required toinhibit corrosion of the metal/metal alloy surface.

In general, the corrosion inhibiting performance of these corrosioninhibitors in industrial water systems (as well as in other systems, forexample, other heat transfer systems, lubricant systems, hydraulic fluidsystems, etc.) may be judged by their passivation and persistencycharacteristics. Improved film persistence is recognized as one of thecriteria for film-forming corrosion inhibitors in view of the economicand ecologic advantages of the commensurate low dose or charge requiredfor corrosion inhibiting compositions that may attain such persistence.Passivation rate is also a relevant criterion for the same reasons. Inother words, those compositions that provide the most valuable corrosioninhibiting films are those which both form quickly, thus minimizing thepresence of the corrosion inhibiting composition in the effluent, aswell as persist for greatest length of time, likewise minimizing theneed to continually charge the corrosion inhibiting composition into thesystem.

SUMMARY

According to a first broad aspect of the present invention, there isprovided a composition comprising a corrosion inhibiting componenthaving:

-   -   one or more tetrahydrobenzotriazoles having the general formulas        Ia or Ib:

-   -   wherein R₁ is one or more of: H, a hydroxy group, or an        aliphatic group; and wherein    -   R₂ is H, or an aliphatic group; or salts of the        tetrahydrobenzotriazoles; and    -   one or more other triazoles having the general formula II:

-   -   wherein R₃ is one or more of: H, a hydroxy group, an aliphatic        group, or an aromatic group; and wherein R₄ is H, or an        aliphatic group; or salts of the other triazoles;    -   wherein the tetrahydrobenzotriazoles are in a weight ratio to        the other triazoles such that the composition decreases the        General Corrosion rate, as measured by copper electrodes in the        presence of 10 ppm sodium hypochlorite, by at least about 0.05        mpy relative to a corrosion inhibitor component comprising 100%        of the other triazoles.

According to a second broad aspect of the present invention, there isprovided a method comprising the following steps:

-   -   (a) providing a composition comprising a corrosion inhibiting        component having:        -   one or more tetrahydrobenzotriazoles having the general            formulas Ia or Ib:

-   -   -   wherein R₁ is one or more of: H, a hydroxy group, or an            aliphatic group; and wherein R₂ is H, or an aliphatic group;            or salts of the tetrahydrobenzotriazoles; and        -   one or more other triazoles having the general formula II:

-   -   -   wherein R₃ is one or more of: H, a hydroxy group, an            aliphatic group, or an aromatic group, R₄ is H, or an            aliphatic group; or salts of the other triazoles;        -   wherein the tetrahydrobenzotriazoles are in a weight ratio            to the other triazoles such that the composition decreases            the General Corrosion rate, as measured by copper electrodes            in the presence of 10 ppm sodium hypochlorite, by at least            about 0.05 mpy relative to a corrosion inhibitor component            comprising 100% of the other triazoles; and

    -   (b) contacting a metal component which comprises a metal or        metal alloy which is corrodible in the presence of copper or        copper corroding agents with a corrosion inhibiting amount of        the composition of step (a) to inhibit corrosion of the metal        component by copper or copper corroding agents.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in conjunction with the accompanyingdrawing, in which:

The FIG. represents a graphical plot of individual data points whichcompare the General Corrosion rates (at 25° C.), as measured by copper(Cu) electrodes, reflected in units of milli-inches per year (mpy), inthe presence of two sequentially added aliquots of 5 ppm sodiumhypochlorite (total of 10 ppm of sodium hypochlorite added), wherein theCu electrodes are “passivated” with (i.e., coated with a film of)compositions comprising 90% by weight of various triazole blends and 10%by weight propylene glycol.

DETAILED DESCRIPTION

It is advantageous to define several terms before describing theinvention. It should be appreciated that the following definitions areused throughout this application.

Definitions

Where the definition of terms departs from the commonly used meaning ofthe term, applicant intends to utilize the definitions provided below,unless specifically indicated.

For the purposes of the present invention, the term “comprising” meansvarious compositions, compounds, ingredients, components, elements,capabilities and/or steps, etc., may be conjointly employed in thepresent invention. Accordingly, the term “comprising” encompasses themore restrictive terms “consisting essentially of” and “consisting of.”

For the purposes of the present invention, the term“tetrahydrobenzotriazoles” (referred to interchangeably herein as“tetrahydrogenated benzotriazoles” or “THBs”) refers to one or morecompounds having the general formulas Ia or Ib:

wherein R₁ is one or more of: H, a hydroxy group, or an aliphatic group;and wherein R₂ is H, or an aliphatic group; as well as salts of thesecompounds of formulas Ia or Ib. The aliphatic R₁ groups may be at one ormore of the 4, 5, 6 and/or 7 positions on the cyclohexane ring. In thesome embodiments, R₁ may be one aliphatic group, with the remaining R₁being H. The salts of these tetrahydrobenzotriazoles may include, forexample, the sodium salts, the potassium salts, the ammonium salts, etc.These tetrahydrobenzotriazoles may include, for example,tetrahydrobenzotriazole (i.e., 4,5,6,7-tetrahydro-benzotriazole, alsoreferred herein interchangeably as “THBT”), tetrahydrotolyltriazole(referred to herein interchangeably as tetrahydrotoluoyltriazole or“THTT) which may be 4-methyl-1H-benzotriazole,5-methyl-1H-benzotriazole, or a mixture thereof; sodium, potassium, orammonium salts of THBT or THTT; etc., as well as blends, mixtures, etc.,of these tetrahydrobenzotriazoles. See, for example, U.S. Pat. No.3,597,353 (Randell et al.), issued Aug. 3, 1971; and U.S. Pat. No.3,849,433 (Butula et al.), issued Nov. 19, 1974, the entire contents anddisclosures of which are herein incorporated by reference, for how toprepare tetrahydrobenzotriazoles from the respective benzotriazoles bycatalytic hydrogenation, and which may also provide residualunhydrogenated benzotriazoles as the other triazoles for embodiments ofcompositions of the present invention.

For the purposes of the present invention, the term “other triazoles”refers to one or more compounds having the general formula

wherein R₃ is one or more of: H, a hydroxy group, an aliphatic group, oran aromatic group, R₄ is H, or an aliphatic group; as well as salts ofthese compounds of formula II (e.g., sodium salts, potassium salts,ammonium salts, etc.). The one or more R₃ groups may be at one or moreof the 4, 5, 6 and/or 7 positions on the benzene ring. In the someembodiments, R₃ may be one aliphatic group, with the remaining R₃ beingH. These other triazoles may include benzotriazole (referred to hereininterchangeably as “BT”), tolyltriazole (referred to hereininterchangeably as toluoyltriazole or “TT”) which may be4-methyl-benzotriazole (referred to herein interchangeably as “4-MeBT”);5-methyl-benzotriazole (referred to herein interchangeably as “5-MeBT”),or a mixture thereof; butyl-benzotriazole (referred to hereininterchangeably as “BBT”) which may be, for example,4-butyl-benzotriazole, 5-butyl-benzotriazole, or a mixture thereof;pentoxy-benzotriazole (referred to herein interchangeably as “PentoxyBT”) which may be 4-pentoxy-benzotriazole (referred to hereininterchangeably as “4-Pentoxy BT”), 5-pentoxy-benzotriazole (referred toherein interchangeably as “5-Pentoxy BT”), or a mixture thereof;carboxy-benzotriazole (referred to herein interchangeably as “CarboxyBT”) which may be 4-carboxy-benzotriazole (referred to hereininterchangeably as “4-Carboxy BT”), 5-carboxy-benzotriazole (referred toherein interchangeably as “5-Carboxy BT”), or a mixture thereof aseither the acid(s) or a water-soluble salt(s) thereof (e.g., sodiumsalt, potassium salt, etc.);N-1-bis(2-ethylhexyl)-aminomethyl-tolyltriazole (e.g., sold by CibaSpecialty Chemicals under the trade name Irgamet 39®);N-1-bis(2,2′-ethanol)-aminomethyl-tolyltriazole (e.g., sold by CibaSpecialty Chemicals under the trade name Irgamet 42®); sodium,potassium, or ammonium salts of, for example, TT, BT, or BBT; etc.

For the purposes of the present invention, the term “aliphatic” refersto a carbon-containing moiety other than an aromatic moiety. Aliphaticmoieties may be straight chain, branched chain, cyclic (cycloaliphatic),or any combination thereof, may be substituted or unsubstituted, mayinclude one or more heteroatoms (e.g., oxygen atoms, nitrogen atoms,sulfur atoms, etc.) in the carbon chain (i.e., may be heterocyclic), maybe unsaturated (i.e., one, two or more double bonds) or saturated, etc,and may have any desired number of carbon atoms, e.g., from 1 to 30carbon atoms, for example from 1 to 12 carbon atoms, such as from 1 to 7carbon atoms, (e.g., from 1 to 4 carbon atoms), etc. Aliphatic moietiessuitable herein may include, but are not limited to, substituted orunsubstituted alkyl, alkenyl, alkadienyl, alkynyl, cycloalkyl,cycloalkenyl, etc. Suitable aliphatic moieties may include, but are notlimited to, straight or branched chain alkyl (e.g., methyl, ethyl,propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, heptyl, etc.) andsubstituted alkyl (e.g., hydroxylmethyl, hydroxyethyl, trifluoromethyl,alkoxymethyl, etc.), alkoxy, substituted amino (e.g., dimethylamino,etc.), carboxy, ester, amide, sulfonamide, carbamate, acyl (i.e.,aldehyde or keto), etc., or any combination thereof.

For the purposes of the present invention, the term “aromatic” refers toan unsaturated cyclic arene moiety containing one or more unsaturatedcyclic rings (for example, 5 and/or 6 atoms per ring) that may besubstituted, unsubstituted, or a combination thereof, may beheterocyclic (i.e., including one or more oxygen atoms, nitrogen atoms,sulfur atoms, etc.), nonheterocyclic, or a combination thereof, may haveany desired number of carbon atoms, e.g., from 3 to 30 carbon atoms, forexample, from 3 to 18 carbon atoms, e.g., from 3 to 12 carbon atoms,etc. Aromatic moieties suitable herein may include, but are not limitedto, substituted or unsubstituted phenyl, naphthyl, biphenyl, binaphthyl,phenanthenryl, anthracenyl, pyridinyl, pyrimidinyl, purinyl, pyrinyl,furanyl, thiophenyl, benzofuranyl, benzothiophenyl, dibenzofuranyl,dibenzothiophenyl, imidazolyl, oxazolyl, thiazolyl, pyrazolinyl,indolyl, pyridazinyl, pyrazinyl, quinolinyl, isoquinolinyl,benzoquinolinyl, phenanthrolinyl (e.g., 1,10-phenanthrolyl), carbazolyl,etc. Suitable aromatic moieties may include, but are not limited to,aromatics substituted with straight or branched chain alkyl (e.g.,methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl,heptyl, etc.) and substituted alkyl (e.g., hydroxymethyl, hydroxyethyl,trifluoromethyl, alkoxymethyl, etc.), amino and substituted amino (e.g.,dimethylamino, etc.), hydroxy (e.g., a phenolic), carboxy, sulfonate,ester, amide, sulfonamide, carbamate, acyl (i.e., aldehyde or ketone),nitro, etc., or any combination thereof.

For the purposes of the present invention, the term“tetrahydrobenzotriazole activating solvents” refers to those solventswhich enhance, improve, reduce the variability of, etc., the corrosioninhibiting ability, effectiveness, etc., of tetrahydrobenzotriazoles.These tetrahydrobenzotriazole activating solvents are generally polarand are capable of solubilizing the tetrahydrobenzotriazoles, as well asother triazoles. These tetrahydrobenzotriazole activating solvents mayinclude one or more of the following: aliphatic alcohols having, forexample, from 1 to 6 carbon atoms, such as methanol, ethanol, propanol,isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol,isohexanol, etc.; low-molecular weight hydroxyl-containing polyolcompounds, such as propylene glycol (1,2-propylene glycol and/or1,3-propylene glycol), ethylene diglycol, diethylene glycol, triethyleneglycol, dipropylene glycol, butylene glycol, butyl diethylene glycol,glycerol, etc.; monoethers of glycols such as methyl, ethyl, propyland/or butyl monoethers of ethylene glycol, diethylene glycol, propyleneglycol, dipropylene glycol, etc.; higher molecular weight nonionicalkylene oxide polyol adduct(s) having a molecular weight of more thanabout 400, such as, for example, polyethylene glycol, polypropyleneglycol, random-added polypropylene polyethylene glycols, or blockcopolymers of ethylene and propylene oxide sometimes referred to aspoloxamers (e.g., Pluronics®); etc.

For the purposes of the present invention, the term “metal component”refers to any part, piece, tool, machine, etc., which comprises one ormore metals or metal alloys. Metal components may include heatexchangers, pumps, pump impellers, stators, valve parts, evaporators,boilers, metal working tools, containers, drums, barrels, pipe, ducts,drums, cylinders, conduits, plumbing, etc.

For the purposes of the present invention, the term “metal or metalalloy which is corrodible in the presence of copper or copper corrodingagents” refers to a metal or metal alloy which, when in contact with,exposed to, etc., copper (e.g., copper ions) or a copper corrodingagent, may lose at least a portion of the metal or metal alloy due to achemical or an electrochemical corrosive process. In the case of metalsor metal alloys which include one or more of aluminum, steel, iron,(e.g., cast iron), silver, etc., which may corrode in the presence ofcopper, the corrosive process is primarily electrochemical where, forexample, copper ions “plate out” from an electrolytic solution onto themetal or metal alloy and thus cause “galvanic corrosion.” In the case ofmetals or metal alloys such as copper, brass, bronze, etc., whichcorrode in the presence of a copper corroding agent (e.g.,hypochlorite), the corrosive process is primarily chemical where, forexample, copper is dissolved from the surface of the metal component,and forms copper ions in the fluid in contact with the metal componentsurface.

For the purposes of the present invention, the term “galvanic corrosion”refers conventionally to an electrochemical process in which one metalcorrodes preferentially when in electrical contact with a different typeof metal, and wherein both metals are immersed in, in contact with, inthe presence of, etc., an electrolyte-containing fluid.

For the purposes of the present invention, the term “corrosioninhibitor” refers to a material, substance, composition, compound,component, etc., which reduces, decreases, diminishes, lowers,minimizes, etc., the rate of corrosion (e.g., General Corrosion rate) ofa metal or metal alloy from the surface of a metal component in thepresence of copper or a copper corroding agent.

For the purposes of the present invention, the term “corrosioninhibiting amount” refers to an amount of a material, substance,composition, compound, component, etc., which is effective to provide ameasurable degree of reduction, diminution, drop, decrease, etc., in therate of corrosion (e.g., General Corrosion) of metal or metal alloy fromthe surface of a metal component in the presence of copper or a coppercorroding agent.

For the purposes of the present invention, the term “aqueous system”refers to any system containing metals which contain or are in contactwith aqueous fluids on a regular basis. Aqueous systems may include openrecirculating cooling systems which obtain their source of cooling byevaporation, closed loop cooling systems, boilers and similar steamgenerating systems, heat exchange equipment, reverse osmosis equipment,oil production systems, flash evaporators, desalinization plants, gasscrubbers, blast furnaces, paper and pulp processing equipment, steampower plants, geothermal systems, food and beverage processingequipment, sugar evaporators, mining circuits, bottle washing equipment,soil irrigation systems, closed circuit heating systems for residentialand commercial use, aqueous-based refrigeration systems, down-wellsystems, aqueous machining fluids (e.g., for use in boring, milling,reaming, broaching, drawing, turning, cutting, sewing, grinding and inthread-cutting operations, or in non-cutting shaping, spinning, drawing,or rolling operations), aqueous scouring systems, aqueous glycolanti-freeze systems, water/glycol hydraulic fluids, ferrous-surfacepre-treatment, polymer coating systems, etc. These aqueous systems mayinclude various sources of water, for example, fresh water, brackishwater, sea water, brines, sewage effluents, industrial waste waters,etc.

For the purposes of the present invention, the term “oxidants” refers tomaterials, substances, compositions, compounds, etc., which are presentin or added to, for example, aqueous systems to oxidize other componentspresent in these systems, for example, are used as biocides for aqueoussystems. These oxidants may include, for example, chlorine-containingoxidants, such as, for example, chlorine, chlorine dioxide, sodiumchlorite, hypochlorous acid, hypochlorites (e.g., sodium hypochlorite,calcium hypochlorite, etc.), chlorine bleach, etc.,nonchlorine-containing oxidants such as acids (e.g., sulfuric acid,nitric acid, etc.), caustics (e.g., sodium hydroxide, potassiumhydroxide, etc.), nonchlorine bleach, peroxides (e.g., hydrogenperoxide, sodium peroxide, etc.), ozone, etc.

For the purposes of the present invention, the term “copper corrodingagent” refers to materials, substances, compositions, compounds, etc.,which causes, increases, etc., loss of copper (including copper presentin copper alloys such as brass, bronze, etc.) from the surface of metalcomponents. These copper corroding agents may include, for example,chlorine-containing oxidants such as chlorine, chlorine dioxide, sodiumchlorite, hypochlorous acid, hypochlorites, (e.g., sodium hypochlorite,calcium hypochlorite, etc.), chlorine bleach, etc., as well snonchlorine-containing oxidants such acids (e.g., sulfuric acid, nitricacid, etc.), caustics (e.g., sodium hydroxide, potassium hydroxide,etc.), nonchlorine bleach, peroxides (e.g., hydrogen peroxide, sodiumperoxide, etc.), ozone, etc.

For the purposes of the present invention, the term “organic fluid”refers to those fluids (other than tetrahydrobenzotriazoles, othertriazoles, and tetrahydrobenzotriazole activating solvents) whichcomprise at least carbon and hydrogen, (e.g., hydrocarbon), but whichmay comprise other atoms such as oxygen, nitrogen, halogen, etc. Theseorganic fluids may include, for example, one or more of: petroleum,petroleum derivatives and petroleum distillates (e.g., mineral oil,lubricating oils, etc.); animal fats; plant oils; synthetic oils (e.g.,polyol esters, alkylated naphthalenes, alkylated benzenes, etc.);hydroprocessed oils; etc., which may function as lubricants, coolants,metal working fluids, anti-wear fluids, anti-friction fluids, etc.

For the purposes of the present invention, the term “metal workingfluid” refers to any fluid which is liquid and which may be used in ametal working process for one or more functions, which may includecooling, lubrication, debris removal, reducing or inhibiting corrosion,reducing or inhibiting material build up on workpieces and/or metalworking tools, etc. Metal working fluids may also be referred tointerchangeably as a “cutting fluid,” a “cutting oil,” a “cuttingcompound,” etc. The metal working fluid may be aqueous, may be anoil-in-water emulsion, may be a paste, may be a gel, may be a mist, etc.These metal working fluids may include water (for example, in amounts offrom 5 to about 70% by weight, such as from about 15 to about 50% byweight of the metal working fluid), conventional coolants and lubricantssuch as, for example, one or more of: a monocarboxylic acid(s), whichmay have more than 10 carbon atoms, such as fatty acids having from 12to 18 carbon atoms; an aromatic or paraffinic carboxylic acid, such as,for example, an alkylsulfuramido carboxylic acid, an arylsulfuramidocarboxylic acid, alkenyl dicarboxylic acid, and/or a alkylphenylcarboxylic acid disclosed in, for example, U.S. Pat. No. 4,315,889(McChesney et al.), issued Feb. 16, 1982, the entire disclosure andcontents of which is hereby incorporated by reference; a petroleumdistillate(s) (e.g., mineral oil), an animal fat(s), a plant oil(s),etc. The amount of the lubricant/coolant may comprise, for example, fromabout 1 to about 30% by weight of the metal working fluid.

For the purposes of the present invention, the term “metal working tool”refers to any tool which causes primarily physical changes, as opposedto chemical changes, to a workpiece. Metal working tools may include,for example, drills, drill presses, mills, cutters, planers, lathes,shapers, borers, reamers, grinders, stamping press, scrapers, etc.

For the purposes of the present invention, the term “metal workingprocess” refers to any mechanical process which uses a metal workingtool. Such processes may include, for example, drilling, milling,cutting, planing, machining, shaping, stamping, grinding, lathing,trimming, abrading, boring, reaming, polishing, turning, honing, sawing,broaching, tapping, threading etc., or any combination thereof.

For the purposes of the present invention, the term “passivation” refersto the formation of a film which lowers the corrosion rate (e.g.,General Corrosion rate) of the metallic surface being treated, usuallyby continuously or intermittently charging a dose of the film formingmaterial directly into the water of the system to be treated.

For the purposes of the present invention, the term “passivation rate”refers to the time required to form a protective film on a metallicsurface.

For the purposes of the present invention, the term “persistency” refersto the length of time a protective film is present on a metal/metalalloy surface when a corrosion inhibitor is not present in the fluidsystem (e.g., an aqueous system) which is in contact with the protectedmetal/metal alloy surface.

For the purposes of the present invention, the term “mpy,” refers to“milli-inch per year” and is used herein as a unit of measurement of theGeneral Corrosion rate of metal/metal alloy surfaces in the presence ofcopper or a copper corroding agent such as sodium hypochlorite.

For the purposes of the present invention, the term “General Corrosion”(also called “Uniform Corrosion”) refers to corrosion which takes placeuniformly over the surface of metal/metal alloy surfaces in the presenceof a corrosive agent, thereby causing a uniform removal of metal/metalalloy from the surface and thus a general thinning of the componentcomprising the metal/metal alloy. General Corrosion should be contrastedwith “localized corrosion” such as pitting corrosion, crevice corrosion,etc. General Corrosion rates are measure herein as described in theMeasurement of General Corrosion Rates section described below.

For the purposes of the present invention, the amounts referred toherein in terms of weight percent for the tetrahydrobenzotriazoles,other triazoles, tetrahydrobenzotriazole activating solvents, etc.,refer to single strength usage amounts where the composition is in aready to use form. Accordingly, the compositions comprising thesetetrahydrobenzotriazoles, other triazoles, tetrahydrobenzotriazoleactivating solvents, etc., may also be in concentrate form in amountswhich provide, after appropriate dilution with, for example, water,organic fluids, etc., single strength usage compositions having therequisite weight percent ranges of tetrahydrobenzotriazoles, othertriazoles, tetrahydrobenzotriazole activating solvents, etc., ashereafter specified.

For the purposes of the present invention, the formulas used in thespecification, in the claims or in the drawings may represent a singlecompound, a mixture of compounds, etc., unless otherwise specified.

Description

Copper corrosion issues may occur in various forms. For example, coppercorrosion may occur in one of two general forms, one direct and oneindirect. In the direct form of copper corrosion, a metal componentcomprising copper or copper alloy may be chemically attacked by a coppercorroding agent such as chlorine, a hypochlorite, etc., which may beused, for example, as an oxidizing biocide in, for example, anindustrial water system. Direct chemical attack on the surface of themetal component may cause a general thinning and weakening of thecomponent due to loss of copper metal (i.e., General Corrosion), or maycause localized corrosion (e.g., pitting corrosion crevice corrosion,etc.) of the metal component. In addition to causing thinning andweakening of the metal component, direct copper corrosion may create anincreasingly concentrated copper-containing effluent in any fluid (e.g.,water) which comes into contact with the corroding metal component.Disposing of this copper-containing effluent may pose a significantenvironmental and toxicity problem. Also, the copper-containing effluentmay itself catalytically attack organic (e.g., hydrocarbon)-containingmaterials present in the effluent or in other components in the system,thus causing other undesirable effects.

In the indirect form of copper corrosion, copper ions present in thefluid (e.g., from direct corrosion of metal components) may come intocontact with other metal components. These other metal components maycomprise metal or metals alloys such as aluminum, steel, iron, etc.,which, when contacted with the fluid carrying the copper ions, may causethe copper ion to “plate out” on the surface of the metal component.Because many of such copper ion-containing fluids may also function aselectrolytes, the copper that “plates out” on the metal component maythen cause an electrochemical process of galvanic corrosion where thealuminum, iron, steel, etc., is electrochemically dissolved from thesurface of the metal component to again cause general thinning/weakening(i.e., General Corrosion) of the metal component, as well as localizedcorrosion (e.g., pitting corrosion crevice corrosion, etc.) thereof.

Embodiments of the corrosion inhibiting compositions and methods of thepresent invention are directed at controlling, and especiallyinhibiting, the corrosive effects of copper due to either direct orindirect corrosion of copper or copper alloys. Certain benzotriazolessuch as benzotriazole (“BT”) and tolyltriazole (“TT”) are commonly usedas corrosion inhibitors for protecting metal/metal alloy components,such as those comprising copper and copper alloys (e.g., brass), fromdirect corrosion caused by copper corroding agents. These benzotriazolesmay also be used to “scavenge” copper present in the fluids circulatingthrough these systems to minimize, reduce, decrease, etc., indirectgalvanic corrosion of metal/metal alloy components (e.g., thosecomprising aluminum, iron, steel, etc.) caused by the copper in suchfluids “plating out.” But even when such metal/metal alloy componentsprotected by such benzotriazoles (e.g., as a protective film on thesurface of the component) are exposed to, for example, oxidizingbiocides such as chlorine, hypochlorite, etc., the corrosion protectionof these films may break down. After such breakdown, it may be difficultto form new protective benzotriazole films in these aqueous systems thatare periodically or continuously supplied with oxidizing biocides suchas chlorine, hypochlorite, etc. Very high dosages of, for example,tolyltriazole (TT) may be applied in an attempt to improve corrosioninhibition performance, but may provide limited success.

What has been discovered to be surprising with respect to theembodiments of the corrosion inhibiting compositions of the presentinvention is that the corrosion inhibition properties of thesebenzotriazoles with respect to direct corrosion of copper and copperalloys (including minimizing, reducing, decreasing, etc., the effects ofdissolved copper present in the effluent such as catalytically attackingorganic materials, creating environmental and toxicity issues, etc.), aswell as indirect galvanic corrosion caused by copper ions “plating out”on other metals and metal alloys, such as aluminum, iron, steel, etc.,may be further improved by blending in certain minimal amounts ofcertain tetrahydrobenzotriazoles, such tetrahydrotoluoyltriazole(“THTT”), even in the presence of, for example, oxidizing biocides suchas chlorine, hypochlorite, etc. In fact, it has been surprisingly foundthat in embodiments of corrosion inhibition compositions of the presentinvention that the combination of, for example, tetrahydrotolyltriazole(“THTT”) with a blend of benzotriazole (“BT”) and tolyltriazole (“TT”),performs better as a corrosion inhibitor than simply using THTT alone.What has also been found to be particularly surprising is that amountof, for example, THTT should be adjusted appropriately, relative to theamount of, for example, BT/TT in terms of how much THTT should beblended with BT/TT, to provide improved corrosion inhibition.

In addition, in some embodiments, it has been additionally discoveredthat the use of certain tetrahydrobenzotriazole activating solvents,such as propylene glycol, and polypropylene glycol, etc., may minimize,reduce, lessen, diminish, avoid, prevent, eliminate, etc., thepotentially “variable” corrosion inhibiting properties of thesetetrahydrobenzotriazoles, even when these tetrahydrobenzotriazoles areused in combination with these other triazoles. These benefits may beachieved by solubilizing these tetrahydrobenzotriazoles in thesetetrahydrobenzotriazole activating solvents, such as propylene glycol,polypropylene glycol, etc. Solubilization of thesetetrahydrobenzotriazoles in these activating solvents minimizes,reduces, lessens, diminishes, avoids, prevents, eliminates, etc.,micelle formation of these tetrahydrobenzotriazole in the presence of,for example, aqueous systems, and thus keeps thesetetrahydrobenzotriazoles “active” as corrosion inhibitors when use incombination with these other triazoles. See co-pending U.S. applicationSer. No. 13/045,580 (to William N. Matulewicz et al.), filed Mar. 11,2011, the entire disclosure and contents of which is herein incorporatedby reference.

Embodiments of the corrosion inhibiting compositions of the presentinvention may comprise, for example, from about 10 to about 100%, suchas from about 10 to about 90% (e.g., from about 35 to about 70%) byweight of the composition of a corrosion inhibitor component whichcomprises: one or more tetrahydrobenzotriazoles (having the generalformulas Ia/Ib defined above, including salts of thesetetrahydrobenzotriazoles); and one or more other triazoles (having thegeneral formula II defined above, including salts of these othertriazoles). The weight ratio of the tetrahydrobenzotriazoles to theother triazoles are such that the composition decreases the GeneralCorrosion rate, as measured by copper electrodes in the presence of 10ppm sodium hypochlorite, by at least about 0.05 mpy (for example, atleast about 0.3 mpy, such as at least about 0.5 mpy) relative to acorrosion inhibitor component comprising 100% of the other triazoles.For example, the weight ratio of these tetrahydrobenzotriazoles to theseother triazoles may be in the range of from about 1:89 to about 1:8,such as from about 1:89 to about 1:12 (e.g., from about 1:44 to about1:14).

Embodiments of the corrosion inhibiting components comprising the one ormore tetrahydrobenzotriazoles with the other triazoles may be preparedsimply by blending together the constituent compounds or by blendingtogether the precursors of the constituent compounds and thenhydrogenating those precursors. Initial hydrogenation of, for example,the methylbenzotriazole isomers may be accomplished by catalytichydrogenation processes known in the art. See, for example, U.S. Pat.No. 3,597,353 (Randell et al.), issued Aug. 3, 1971; and U.S. Pat. No.3,849,433 (Butula et al.), issued Nov. 19, 1974, the entire contents anddisclosures of which are herein incorporated by reference, for how toprepare tetrahydrobenzotriazoles from the respective benzotriazoles bycatalytic hydrogenation, and which may also provide residualunhydrogenated benzotriazoles as the other triazoles for embodiments ofcompositions of the present invention. Commercially available liquidmixtures of THTT (e.g., a mixture of 4-methyl-1H-benzotriazole and5-methyl-1H-benzotriazole) may include the trade name product “CemazolWD-85” available from CEMCO, Inc., the trade name product “COBRATEC928,” available from PMC Specialties Group, Inc., etc.

Embodiments of the corrosion inhibiting compositions of the presentinvention comprising the one or more tetrahydrobenzotriazoles, othertriazoles, and optionally tetrahydrobenzotriazole activating solventsmay also comprise other optional ingredients, and/or may be used withsuch optional ingredients. For example, these optional ingredients mayinclude: water, organic fluids; biocides, fungicides or otherbactericidal agents; extreme pressure additives; antioxidants; othercorrosion inhibitors besides tetrahydrobenzotriazoles and othertriazoles; dyes; water conditioners; pH-controlling agents; perfumes;viscosity-controlling agents; etc.

The embodiments of the compositions of the present invention may be usedin a variety of processes, systems, etc., where metal componentscomprising copper or copper alloy are potentially subject to directcorrosion by being chemically attacked by copper corroding agents, suchas for example, chlorine, a hypochlorite, etc., as well as indirectcopper corrosion where copper ions present in the fluid may come intocontact with metal components comprising metal or metals alloys such asaluminum, steel, iron, etc., on which these copper ions may “plate out”and thus cause galvanic corrosion. These processes, systems, etc., maybe aqueous or nonaqueous, and may include, for example, industrialaqueous processes and systems, heat exchanger/transfer systems, metalworking processes, machining fluid systems, coolant systems (e.g.,cooling water systems), lubricant systems, hydraulic fluid systems,boilers and similar steam generating systems, reverse osmosis processesand systems, oil production processes and systems, flash evaporatorprocesses and systems, desalinization processes and systems, gasscrubber systems, blast furnace systems, paper and pulp processingsystems, food and beverage processing systems, bottle washing processesand systems, soil irrigation systems, aqueous-based closed circuitheating or refrigerant systems, polymer coating systems, sewage effluentsystems, industrial waste water systems, etc.

In embodiments of the method of the present invention, the corrosioninhibiting composition may be used by directly contacting the metalcomponent (e.g., by treating, applying, forming a film, coating,dipping, spraying, wiping, daubing, etc.) with the composition, or byincorporating, adding, blending, mixing, etc., the composition to afluid which contacts the metal component. The amount of the corrosioninhibiting composition to be used to provide corrosion inhibition willdepend on a variety of factors, including, for example, the particularcorrosion inhibition component used and concentration in thecomposition, the particular process, system, etc., that the corrosioninhibiting composition is used with, the degree of potential corrosionexpected in the particular process, system, etc., the manner in whichthe corrosion inhibiting composition is used, added, incorporated, etc.,to inhibit corrosion, etc. For example, providing an amount of thecorrosion inhibiting composition which creates a concentration of atleast about 1 ppm (such as from about 50 to about 1000 ppm of thecomposition, e.g., from about 100 to about 500 ppm of the composition,such as from about 250 to about 500 ppm) of the corrosion inhibitioncomponent in the fluid circulating in the process, system, etc., mayprovide effective corrosion inhibition.

Aspects of the embodiments of the corrosion inhibiting compositions ofthe present invention are illustrated by the graphs shown in the FIG.The FIG. represents a graph, indicated generally as 100, which comparesthe General Corrosion rates (at 25° C.), as measured by copperelectrodes, reflected in units of milli-inches per year (mpy), in thepresence of 10 ppm sodium hypochlorite (added as two separate 5 ppmaliquots) in the aqueous test solution in which the copper electrodes(i.e., cathode, anode and reference electrodes) are immersed. The copperelectrodes are “passivated” for 60 minutes with (i.e., coated with afilm of) each of eight compositions (represented as individual datapoints 101 through 109 positioned along line 112 in graph 100 of FIG. 1)comprising 90% by weight of various blends of tetrahydrotolyltriazole(THTT) with a 50/50 mixture of tolyltriazole (TT)/benzotriazole (BT),along with 10% by weight propylene glycol. After the copper electrodeshave been “passivated” for 60 minutes with each of composition, thefirst 5 ppm aliquot of the sodium hypochlorite is added to eachcomposition. The second 5 ppm aliquot of sodium chlorite is added eachcomposition approximately 15 minutes after the first aliquot. TheGeneral Corrosion rate of each composition is then measured as anindividual data point approximately 3 minutes and 50 seconds after thesecond aliquot of 5 ppm sodium hypochlorite is added.

The various triazole blends for compositions 101 through 109, along withthe respective individual General Corrosion rate data points measured(see Measurement of General Corrosion Rates section below) are shownbelow in Table 1:

TABLE 1 General Corrosion Rate Composition TTHB¹ TT² BT³ (mpy) 101  0%  45%   45% 0.74 (0.00 ppm) (1 ppm) (1 ppm) 102  1% 44.5% 44.5% 0.28(0.02 ppm) (0.99 ppm) (0.99 ppm) 103  2%   44%   44% 0.19 (0.04 ppm)(0.98 ppm) (0.98 ppm) 104  4%   43%   43% 0.09 (0.09 ppm) (0.955 ppm)(0.955 ppm) 105  6%   42%   42% 0.20 (0.13 ppm) (0.935 ppm) (0.935 ppm)106  7% 41.5% 41.5% 0.36 (0.16 ppm) (0.92 ppm) (0.92 ppm) 107  9% 40.5%40.5% 0.52 (0.20 ppm) (0.90 ppm) (0.90 ppm) 108 10%   40%   40% 0.66(0.22 ppm) (0.89 ppm) (0.89 ppm) 109 30%   30%   30% 1.18 (0.67 ppm)(0.665 ppm) (0.665 ppm) ¹Tetrahydrotolyltriazole ²Tolyltriazole³Benzotriazole

The General Corrosion rate data points for compositions 101 through 109from Table 1 above are plotted in graph 100 of FIG. 1 as individual datapoints 101 through 109. As Table 1 and graph 100 in FIG. 1 show,replacing the 50/50 mixture of TT/BT with, for example, 1% to 10% THTT(see data points 102 through 108), or a weight ratio of TTHT to theTT/BT mixture in the range of from about 1:89 to about 1:8, decreasesthe General Corrosion rate, as measured by the Cu Electrodes in thepresence of 10 ppm sodium hypochlorite, by at least 0.05 mpy relative tothe 100% TT/BT mixture (see data point 101). As Table 1 and graph 100 inthe FIG. also show, replacing the 50/50 mixture of TT/BT with, forexample, 1% to 7% THTT (see data points 102 through 106), or a weightratio of TTHT to the TT/BT mixture in the range of from about 1:89 toabout 1:12, decreases the General Corrosion rate, as measured by the CuElectrodes, by at least 0.3 mpy relative to the 100% TT/BT mixture (seedata point 101). As Table 1 and graph 100 in the FIG. further show,replacing the 50/50 mixture of TT/BT with, for example, 2% to 6% THTT(see data points 103 through 105), or a weight ratio of TTHT to theTT/BT mixture in the range of from about 1:44 to about 1:14, decreasesthe General Corrosion rate, as measured by the Cu Electrodes, by atleast 0.5 mpy relative to the 100% TT/BT mixture (see data point 101).

Measurement of General Corrosion Rates

The General Corrosion rates of the corrosion inhibitorcompositions/solutions are measured herein as follow:

Equipment Used:

Pepperl Fuchs Corr Tran MV Unit

Hart Modem, Model HI-321 (Pepperl Fuchs)

99.9% Cu Electrodes (CME-OJ) (Pepperl Fuchs)

Corr Tran MV Unit Operating Conditions Used:

HDA (Harmonic Distortion Analysis) PV Units: mpy Electrode Area: 4.75cm² LRV: 0 mpy K Probe Constant: 11685.71 mm^(x)cm²/y/A URV: 40 mpyMeasurement Mode: GC+Con Alarm: Auto Device Mode: Standard Cyclic/On PVPreference: GeneralSolution/Reagent/Equipment Component Preparation:

-   -   1. Corrosive water solutions are prepared according to ASTM        D1384-05 Specifications    -   2. Preparation of Electrodes: Electrodes (i.e., cathode, anode        and reference electrodes) used for testing are “conditioned” by        using the electrodes a few times and then cleaning electrodes to        obtain the most consistent performance. After electrode use, the        electrodes are removed from the Corr Tran unit and are cleaned        with pumice powder and deionized water until the electrode        surface is free of any inhibitor composition or corrosive film.        The electrodes are rinsed in HCl (0.1N) for ten seconds,        followed by rinsing in deionized water to remove HCl on the        surface, and are then polished with clean paper towels. An air        hose (oil-free) may be used to remove any liquid from the        electrode surface.    -   3. Preparation of Corrosion Inhibitor Compositions/Solutions: An        appropriate quantity of corrosion inhibitor composition/solution        is added to 10.000 ml of HPLC grade methanol.        Procedure for Measuring General Corrosion Rates:

The methanol-containing corrosion inhibitor compositions/solutions areadded in an amount of 1.00 ml to 1 liter of the prepared corrosive watersolution and stirred. After stirring is started, the Cu electrodes(i.e., cathode, anode and reference electrodes) are immersed two inchesbelow the top surface of the corrosive water solution. Corrosion data isthen recorded on Con Tran MV Unit, using the Operating Conditionsdescribed above. After immersion (“passivation”) in the corrosive watersolution for 60 minutes, the first 5 ppm aliquot of sodium hypochlorite(prepared from 6.15% active sodium hypochlorite bleach) to the corrosivewater solution. Approximately 15 minutes after the first aliquot isadded, a second 5 ppm aliquot of sodium hypochlorite (also prepared from6.15% active sodium hypochlorite bleach) is added to the corrosive watersolution. General Corrosion rate data points are recorded for up to 120minutes (2 hours) after initial immersion of the Cu Electrodes in thecorrosive water solution. The General Corrosion rate data recorded maybe used as an individual General Corrosion rate data points (measuredapproximately 3 minutes and 50 seconds after the second aliquot of 5 ppmsodium hypochlorite is added as shown by individual data points 101through 109 of graph 100 in the FIG.), or may be graphically plottedcontinuously.

All documents, patents, journal articles and other materials cited inthe present application are hereby incorporated by reference.

Although the present invention has been fully described in conjunctionwith several embodiments thereof, it is to be understood that variouschanges and modifications may be apparent to those skilled in the art.Such changes and modifications are to be understood as included withinthe scope of the present invention as defined by the appended claims,unless they depart therefrom.

1. A composition comprising a corrosion inhibiting component having: oneor more tetrahydrobenzotriazoles having the general formulas Ia or Ib:

wherein R₁ is one or more of: hydrogen, a hydroxy group, or an aliphaticgroup; and wherein R₂ is hydrogen, or an aliphatic group; or salts ofthe tetrahydrobenzotriazoles; and one or more other triazoles having thegeneral formula II:

wherein R₃ is one or more of: hydrogen, a hydroxy group, aliphaticgroup, or an aromatic group' and wherein R₄ is hydrogen, or an aliphaticgroup; or salts of the other triazoles; wherein thetetrahydrobenzotriazoles are in a weight ratio to the other triazoles inthe range of from about 1:89 to about 1:8 and such that the compositiondecreases the General Corrosion rate, as measured by copper electrodesin the presence of 10 ppm sodium hypochlorite, by at least about 0.05mpy relative to a corrosion inhibitor component comprising 100% of theother triazoles; and wherein the corrosion inhibiting componentcomprises from about 10 to 100% of the composition.
 2. The compositionof claim 1, wherein the one or more tetrahydrobenzotriazoles are one ormore of: tetrahydrobenzotriazole; or tetrahydrotolyltriazole.
 3. Thecomposition of claim 2, wherein the one or more tetrahydrobenzotriazolesare tetrahydrotolyltriazole.
 4. The composition of claim 1, wherein theone or more other triazoles are one or more of: benzotriazole; a sodiumsalt of benzotriazole; tolyltriazole; a sodium salt of tolyltriazole;pentoxy-benzotriazole; carboxy-benzotriazole;N-1-bis(2-ethylhexyl)-aminomethyl-tolyltriazole; orN-1-bis(2,2′-ethanol)-aminomethyl-tolyltriazole.
 5. The composition ofclaim 1, wherein the one or more other triazoles are a mixture ofbenzotriazole and tolyltriazole, or a mixture of the sodium salts ofbenzotriazole and tolyltriazole.
 6. The composition of claim 1, whereinthe weight ratio of the tetrahydrobenzotriazoles to the other triazolesis in the range of from about 1:89 to about 1:12.
 7. The composition ofclaim 6, wherein the weight ratio of the tetrahydrobenzotriazoles to theother triazoles is in the range of from about 1:44 to about 1:14.
 8. Thecomposition of claim 1, wherein weight ratio of thetetrahydrobenzotriazoles to the other triazoles is such that thecomposition decreases the General Corrosion rate, as measured by thecopper electrodes in the presence of 10 ppm sodium hypochlorite, by atleast about 0.3 mpy relative to the corrosion inhibitor componentcomprising 100% of the other triazoles.
 9. The composition of claim 8,wherein weight ratio of the tetrahydrobenzotriazoles to the othertriazoles is such that the composition decreases the General Corrosionrate, as measured by the copper electrodes in the presence of 10 ppmsodium hypochlorite, by at least about 0.5 mpy relative to the corrosioninhibitor component comprising 100% of the other triazoles.
 10. Thecomposition of claim 1, wherein the corrosion inhibiting componentcomprises from about 35 to about 70% of the composition.